If Liz Cheney, whose bid for the Senate has always had a stench of extreme opportunism, wants to discuss traditions and values, I’m all for it. Let’s start here: Isn’t there a tradition of close-knit family members taking care not to wound one another? Is there not value in that?

From the moment that Liz decided, from the perch of her longtime home in the Virginia suburbs of Washington, to act the part of an honest-to-goodness Wyoming resident and challenge an incumbent senator (and family friend) from that state, she must have known that the issue of same-sex marriage would come up. It is, after all, a prominent thread in the news. It’s also a prominent thread in stories about her family, given that her father, Dick, bucked his party to become an early Republican supporter of same-sex marriage, and given that her lone sibling, Mary, has a female spouse.

She must also have entertained speaking out against it, because that’s what she ended up doing Sunday, on Fox News, saying that she believed “in the traditional definition of marriage.” And she must have foreseen that this would pain Mary, who was married last year and whose two children are being brought up with the understanding that their family has the same dignity as any other.

But she plunged forward anyway, disregarding the inevitable discord. As Jonathan Martin reported in The Times, Liz and Mary aren’t speaking to each other now, and there’s a long shadow over the Cheneys’ holiday get-togethers.

Is any political office worth that? Would victory redeem the public message that Liz just sent to her niece and nephew? I’m imagining her awkwardness the next time that she goes to hug or kiss them (and I’m assuming that she’s a hugger or kisser, which may be a leap). If there’s not a knot in her stomach, then there’s nothing at all in her heart.

Having a lesbian sister doesn’t compel her to support marriage equality. Having a gay relative doesn’t compel anyone to. There are earnest divisions here, often driven by deep-seated religious convictions.

But Liz’s decision to chart a course and publicize a view bound to offend her sister is entirely volitional. It’s also entirely different from airing other ideological disagreements within families. Conflicting views on abortion or the death penalty don’t challenge the very structure and foundation of a loved one’s home. Questioning the validity of a marriage does. You’re not saying that you part with the way someone thinks. You’re saying that you have qualms with who they are, and this is a statement — a sentiment — you can keep to yourself. Even once Liz had elected to run, she could have chosen to say that the issue of gay marriage wasn’t going to be part of her campaign.

Is she even being genuine in her opposition? In a 2009 interview about gay marriage on MSNBC, she said that “freedom means freedom for everybody.” On Monday I talked with three people who worked with her in the Bush administration, and all were very surprised by her current stance. They’d had the strong impression that she favored same-sex marriage.

Perhaps Mary and her wife, Heather Poe, did as well, because Poe wrote this on Facebook after Liz’s appearance on Fox News: “Liz has been a guest in our home, has spent time and shared holidays with our children, and when Mary and I got married in 2012 — she didn’t hesitate to tell us how happy she was for us.”

Happy back then, self-serving and seemingly cowardly now. This feels to me like a political maneuver tailored to a conservative electorate, and an unnecessary maneuver at that, with the risk of making her seem inauthentic and uncharitable to Wyoming voters who’ve had more than a decade to absorb her dad’s socially moderate views. Gay marriage won’t be those voters’ primary, secondary or tertiary issue, anyway.

In a statement released Monday, Dick and Lynne Cheney insisted that Liz had “always believed in the traditional definition of marriage.” I suppose that’s the politically prudent tack at this point, but now the Cheneys’ support for gay marriage, so moving over the years, is buried beneath a family feud. Their statement paid less attention to Mary, who’s not running for anything, not carrying her parents’ ambitions into a new era.

One word stood out. They said that Liz had shown Mary “compassion.” This echoed a statement of Liz’s own, in which she noted that she had “always tried to be compassionate” toward Mary and her family. What a curious vocabulary. It was as if they were all talking about some charity case.

I hope the Cheneys find their way out of this. It’s an ugly spot that Liz, in all her compassion, has put them in.